The temporal dynamics of coherent motion processing in autism spectrum disorder: evidence for a deficit in the dorsal pathway

Visual processing and decision-making in autism and dyslexia: Insights from cross-syndrome approaches

Atypical visual processing has been reported in developmental conditions like autism and dyslexia, and some accounts propose a causal role for visual processing in the development of these conditions. However, few studies make direct comparisons between conditions, or use sufficiently sensitive methods, meaning that it is hard to say whether atypical visual processing tells us anything specific about these conditions, or whether it reflects a more general marker of atypical development. Here I review findings from two computational modelling approaches (equivalent noise and diffusion modelling) and related electroencephalography (EEG) indices which we have applied to data from autistic, dyslexic and typically developing children to reveal how the component processes involved in visual processing and decision-making are altered in autism and dyslexia. The results identify both areas of convergence and divergence in autistic and dyslexic children's visual processing and decision-making, with implications for influential theoretical accounts such as weak central coherence, increased internal noise, and dorsal-stream vulnerability. In both sets of studies, we also see considerable variability across children in all three groups. To better understand this variability, and further understand the convergence and divergence identified between conditions, future studies would benefit from studying how the component processes reviewed here relate to transdiagnostic dimensions, which will also give insights into individual differences in visual processing and decision-making more generally.

Associations Between Autism Spectrum Quotient and Integration of Visual Stimuli in 9-year-old Children: Preliminary Evidence of Sex Differences

PURPOSE

The dorsal stream vulnerability hypothesis posits that the dorsal stream, responsible for visual motion and visuo-motor processing, may be particularly vulnerable during neurodevelopment. Consistent with this, autism spectrum disorder (ASD) has been associated with deficits in global motion integration, though deficits in ventral stream tasks, such as form identification, have also been reported. In the current study, we examined whether a similar pattern of results is found in a cohort of 381 children born with neurodevelopmental risk factors and exhibiting a wide spectrum of caregiver-reported autistic traits.

METHODS

We examined the associations between global motion perception, global form perception, fine motor function, visual-motor integration, and autistic traits (autism spectrum quotient, AQ) using linear regression, accounting for possible interactions with sex and other factors relevant to neurodevelopment.

RESULTS

All assessments of dorsal stream function were significantly associated with AQ such that worse performance predicted higher AQ scores. We also observed a significant sex interaction, with worse global form perception associated with higher AQ in boys (n = 202) but not girls (n = 179).

CONCLUSION

We found widespread associations between dorsal stream functions and autistic traits. These associations were observed in a large group of children with a range of AQ scores, demonstrating a range of visual function across the full spectrum of autistic traits. In addition, ventral function was associated with AQ in boys but not girls. Sex differences in the associations between visual processing and neurodevelopment should be considered in the designs of future studies.

Global motion processing in infants' visual cortex and the emergence of autism

Autism is a heritable and common neurodevelopmental condition, with behavioural symptoms typically emerging around age 2 to 3 years. Differences in basic perceptual processes have been documented in autistic children and adults. Specifically, data from many experiments suggest links between autism and alterations in global visual motion processing (i.e., when individual motion information is integrated to perceive an overall coherent pattern). Yet, no study has investigated whether a distinctive organization of global motion processing precede the emergence of autistic symptoms in early childhood. Here, using a validated infant electroencephalography (EEG) experimental paradigm, we first establish the normative activation profiles for global form, global motion, local form, and local motion in the visual cortex based on data from two samples of 5-month-old infants (total n = 473). Further, in a sample of 5-month-olds at elevated likelihood of autism (n = 52), we show that a different topographical organization of global motion processing is associated with autistic symptoms in toddlerhood. These findings advance the understanding of neural organization of infants' basic visual processing, and its role in the development of autism.

Decision-making in autism: A narrative review

LAY SUMMARY

Many autistic people report difficulties with real-life decision-making. However, when doing decision-making tests in laboratory experiments, autistic people often perform as well or better than non-autistic people. We review previously published studies on autistic people's decision-making, across different types of tests, to understand what type of decision-making is more challenging. To do this, we searched four databases of research papers. We found 104 studies that tested, in total, 2712 autistic and 3189 comparison participants on different decision-making tasks. We found that there were four categories of decision-making tests that were used in these experiments: perceptual (e.g. deciding which image has the most dots); reward learning (e.g. learning which deck of cards gives the best reward); metacognition (e.g. knowing how well you perform or what you want); and value-based (e.g. making a decision based on a choice between two outcomes that differ in value to you). Overall, these studies suggest that autistic and comparison participants tend to perform similarly well at perceptual and reward-learning decisions. However, autistic participants tended to decide differently from comparison participants on metacognition and value-based paradigms. This suggests that autistic people might differ from typically developing controls in how they evaluate their own performance and in how they make decisions based on weighing up the subjective value of two different options. We suggest these reflect more general differences in metacognition, thinking about thinking, in autism.

Modulation effects of the intact motor skills on the relationship between social skills and motion perceptions in children with autism spectrum disorder: A pilot study

BACKGROUND

An individual with autism spectrum disorder (ASD) has social skill, motor skill, and motion perception deficits. However, the relationship among them was not clarified. Therefore, this study aimed to evaluate the effects of motor skills on social skills and motion perception.

METHODS

Five typically developed children and fourteen children with ASD participated in our study. The N200 component, a brain activity indicating motion perception, was induced in mid-temporal (MT/V5) brain area by watching a random dot kinematograph, and was recorded using a scalp electroencephalogram. Furthermore, the social responsiveness scale (SRS) indicating the social skill deficit, the developmental coordination disorder questionnaire (DCDQ) estimating the developmental coordination disorder (DCD), and the movement assessment battery for children second edition (MABC-2) indicating motor skills were recorded in the children with ASD. A hierarchical multiple regression analysis was conducted to examine the modulation effects of motor skills on the relationship between social skills and motion perception. The dependent variable was the N200 latency, and the independent variables were SRS, MABC-2, and combined MABC-2 and SRS.

RESULTS

The N200 latency was more delayed in children with ASD relative that in typically developed children. Intact balance ability modulated the relationship between social skills and N200 latency in children with ASD. Within the high balance ability, when the social skills worsened, the N200 latency was shortened.

CONCLUSIONS

This is the first report that intact motor skills could modulate the relationship between social skills and motion perception.

Effects of Pulsed-Wave Chromotherapy and Guided Relaxation on the Theta-Alpha Oscillation During Arrest Reaction

The search for the best wellness practice has promoted the development of devices integrating different technologies and guided meditation. However, the final effects on the electrical activity of the brain remain relatively sparse. Here, we have analyzed of the alpha and theta electroencephalographic oscillations during the realization of the arrest reaction (AR; eyes close/eyes open transition) when a chromotherapy session performed in a dedicated room [Rebalance (RB) device], with an ergonomic bed integrating pulsed-wave light (PWL) stimulation, guided breathing, and body scan exercises. We demonstrated that the PWL induced an evoked-related potential characterized by the N2-P3 components maximally recorded on the fronto-central areas and accompanied by an event-related synchronization (ERS) of the delta–theta–alpha oscillations. The power of the alpha and theta oscillations was analyzed during repeated ARs testing realized along with the whole RB session. We showed that the power of the alpha and theta oscillations was significantly increased during the session in comparison to their values recorded before. Of the 14 participants, 11 and 6 showed a significant power increase of the alpha and theta oscillations, respectively. These increased powers were not observed in two different control groups (n = 28) who stayed passively outside or inside the RB room but without any type of stimulation. These preliminary results suggest that PWL chromotherapy and guided relaxation induce measurable electrical brain changes that could be beneficial under neuropsychiatric perspectives.

Global motion evoked potentials in autistic and dyslexic children: A cross-syndrome approach

Atypicalities in psychophysical thresholds for global motion processing have been reported in many neurodevelopmental conditions, including autism and dyslexia. Cross-syndrome comparisons of neural dynamics may help determine whether altered motion processing is a general marker of atypical development or condition-specific. Here, we assessed group differences in N2 peak amplitude (previously proposed as a marker of motion-specific processing) in typically developing (n = 57), autistic (n = 29) and dyslexic children (n = 44) aged 6-14 years, in two global motion tasks. High-density EEG data were collected while children judged the direction of global motion stimuli as quickly and accurately as possible, following a period of random motion. Using a data-driven component decomposition technique, we identified a reliable component that was maximal over occipital electrodes and had an N2-like peak at ~160 msec. We found no group differences in N2 peak amplitude, in either task. However, for both autistic and dyslexic children, there was evidence of atypicalities in later stages of processing that require follow up in future research. Our results suggest that early sensory encoding of motion information is unimpaired in dyslexic and autistic children. Group differences in later processing stages could reflect sustained global motion responses, decision-making, metacognitive processes and/or response generation, which may also distinguish between autistic and dyslexic individuals.

Clinical evaluation of childhood cerebral adrenoleukodystrophy with balint's symptoms

BACKGROUND

Childhood cerebral adrenoleukodystrophy (CCALD) is the most common phenotype of adrenoleukodystrophy (ALD) and is characterized by the progression of intellectual, psychic, visual, and gait disturbances. Progression of this intractable disease can only be prevented by hematopoietic stem cell transplantation during the early stages of the disease. The aim of this study was to clinically evaluate children with CCALD who have visual symptoms to enable early diagnosis.

METHODS

We enrolled 41 Japanese children with CCALD who had visual symptoms. We retrospectively analyzed age of onset, past medical history, initial symptoms, visual symptoms and findings on brain magnetic resonance imaging.

RESULTS

The median age of disease onset was 7 years (range 5-10 years). The most common visual symptom was strabismus (n = 22). There was only one patient with the triad of symptoms of Balint's syndrome. Seventeen patients had incomplete Balint's syndrome and showed one or two of the triad of symptoms. Almost all patients with complete or incomplete Balint's syndrome showed bilateral parieto-occipital white matter lesions.

CONCLUSIONS

CCALD could develop into Balint's syndrome, especially the incomplete form. Therefore, CCALD should be considered when boys show new symptoms, including lack of eye contact or bumping into objects.

Global Motion Perception in Autism Spectrum Disorder: A Meta-Analysis

Visual perception in individuals with autism spectrum disorder (ASD) is often debated in terms of enhanced local and impaired global perception. Deficits in global motion perception seem to support this characterization, although the evidence is inconsistent. We conducted a large meta-analysis on global motion, combining 48 articles on biological and coherent motion. Results provide evidence for a small global motion processing deficit in individuals with ASD compared to controls in both biological and coherent motion. This deficit appears to be present independent of the paradigm, task, dependent variable, age or IQ of the groups. Results indicate that individuals with ASD are less sensitive to these types of global motion, although the difference in neural mechanisms underlying this behavioral difference remains unclear.

Increased white matter metabolic rates in autism spectrum disorder and schizophrenia

Both autism spectrum disorder (ASD) and schizophrenia are often characterized as disorders of white matter integrity. Multimodal investigations have reported elevated metabolic rates, cerebral perfusion and basal activity in various white matter regions in schizophrenia, but none of these functions has previously been studied in ASD. We used ¹⁸fluorodeoxyglucose positron emission tomography to compare white matter metabolic rates in subjects with ASD (n = 25) to those with schizophrenia (n = 41) and healthy controls (n = 55) across a wide range of stereotaxically placed regions-of-interest. Both subjects with ASD and schizophrenia showed increased metabolic rates across the white matter regions assessed, including internal capsule, corpus callosum, and white matter in the frontal and temporal lobes. These increases were more pronounced, more widespread and more asymmetrical in subjects with ASD than in those with schizophrenia. The highest metabolic increases in both disorders were seen in the prefrontal white matter and anterior limb of the internal capsule. Compared to normal controls, differences in gray matter metabolism were less prominent and differences in adjacent white matter metabolism were more prominent in subjects with ASD than in those with schizophrenia. Autism spectrum disorder and schizophrenia are associated with heightened metabolic activity throughout the white matter. Unlike in the gray matter, the vector of white matter metabolic abnormalities appears to be similar in ASD and schizophrenia, may reflect inefficient functional connectivity with compensatory hypermetabolism, and may be a common feature of neurodevelopmental disorders.

Sensory perception in autism

Autism is a complex neurodevelopmental condition, and little is known about its neurobiology. Much of autism research has focused on the social, communication and cognitive difficulties associated with the condition. However, the recent revision of the diagnostic criteria for autism has brought another key domain of autistic experience into focus: sensory processing. Here, we review the properties of sensory processing in autism and discuss recent computational and neurobiological insights arising from attention to these behaviours. We argue that sensory traits have important implications for the development of animal and computational models of the condition. Finally, we consider how difficulties in sensory processing may relate to the other domains of behaviour that characterize autism.

Motion perception: a review of developmental changes and the role of early visual experience

Significant controversies have arisen over the developmental trajectory for the perception of global motion. Studies diverge on the age at which it becomes adult-like, with estimates ranging from as young as 3 years to as old as 16. In this article, we review these apparently conflicting results and suggest a potentially unifying hypothesis that may also account for the contradictory literature in neurodevelopmental disorders, such as Autism Spectrum Disorder (ASD). We also discuss the extent to which patterned visual input during this period is necessary for the later development of motion perception. We conclude by addressing recent studies directly comparing different types of motion integration, both in typical and atypical development, and suggest areas ripe for future research.

Stronger Neural Modulation by Visual Motion Intensity in Autism Spectrum Disorders

Theories of autism spectrum disorders (ASD) have focused on altered perceptual integration of sensory features as a possible core deficit. Yet, there is little understanding of the neuronal processing of elementary sensory features in ASD. For typically developed individuals, we previously established a direct link between frequency-specific neural activity and the intensity of a specific sensory feature: Gamma-band activity in the visual cortex increased approximately linearly with the strength of visual motion. Using magnetoencephalography (MEG), we investigated whether in individuals with ASD neural activity reflect the coherence, and thus intensity, of visual motion in a similar fashion. Thirteen adult participants with ASD and 14 control participants performed a motion direction discrimination task with increasing levels of motion coherence. A polynomial regression analysis revealed that gamma-band power increased significantly stronger with motion coherence in ASD compared to controls, suggesting excessive visual activation with increasing stimulus intensity originating from motion-responsive visual areas V3, V6 and hMT/V5. Enhanced neural responses with increasing stimulus intensity suggest an enhanced response gain in ASD. Response gain is controlled by excitatory-inhibitory interactions, which also drive high-frequency oscillations in the gamma-band. Thus, our data suggest that a disturbed excitatory-inhibitory balance underlies enhanced neural responses to coherent motion in ASD.

Temporal processing as a source of altered visual perception in high autistic tendency

Superior local at the expense of global perception characterises vision in autism spectrum disorders (ASD). However, progress towards discovering a neural mechanism has been slow. Here we used known differences in magnocellular and parvocellular receptive field properties to assess the temporal encoding of information, via flicker fusion paradigms, in those high and low in self-reported autistic tendency (Autism Spectrum Quotient - AQ). A Low AQ group (AQ≤13, n=22), and a High AQ group (AQ≥18, n=17) undertook a 4AFC luminance flicker fusion (FF) with 5 temporal contrasts from 5% to 100%, and a 2AFC isoluminant red-green colour fusion task. Both groups showed an increase in fusion thresholds with temporal achromatic contrast. The High AQ group displayed diminished flicker fusion thresholds compared to the Low AQ at the lowest contrasts. For the red-green colour fusion task, the High AQ group displayed mean fusion frequency slightly greater than the Low AQ group. A significant interaction between 5% luminance contrast and the red-green fusion frequencies demonstrated that the differences in thresholds were not simply due to variations in overall attentional capacity between groups. These differences in flicker fusion thresholds are in accordance with reported differences in cortical visual evoked potential nonlinearities, particularly relating to the neural efficiency of the magnocellular pathway.